CN104049474A - Nano focus detection method for stacked gate stripe phase analysis - Google Patents
Nano focus detection method for stacked gate stripe phase analysis Download PDFInfo
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- CN104049474A CN104049474A CN201410308999.6A CN201410308999A CN104049474A CN 104049474 A CN104049474 A CN 104049474A CN 201410308999 A CN201410308999 A CN 201410308999A CN 104049474 A CN104049474 A CN 104049474A
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- 238000001514 detection method Methods 0.000 title claims abstract description 13
- 238000004458 analytical method Methods 0.000 title claims description 9
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 15
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 15
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- 238000003384 imaging method Methods 0.000 claims abstract description 14
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- 238000001459 lithography Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
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Abstract
The invention provides a nanometer focus detection method for phase resolution of stacked grating stripes, which is characterized in that an illumination system expands beams and then introduces the beams into a light path through an optical fiber, a marked grating is uniformly illuminated through a condenser, the marked grating passes through a first telecentric imaging system and then is imaged on the surface of a silicon wafer through a prism, and the marked grating passes through the prism and a second telecentric imaging system after being reflected; the light path is divided into two branches by a beam splitter prism, the two branches have the same structure, each branch of light path passes through a transverse shear plate, an interference pattern and a target image formed by parallel flat plates are modulated by a detection grating, the modulated light intensity is subjected to sinusoidal change caused by the movement of the focal plane position of a silicon wafer through an analyzer and then demodulated by a photoelectric detector and a circuit, the phase change of a marking grating is solved according to the sinusoidal change of the light intensity of the two branches of light paths, the translation amount of the marking grating image is determined, and therefore the variation amount of the focal plane position is solved.
Description
Technical field
The invention belongs to the grating focusing test technology in projection lithography apparatus field, be specifically related to the nanometer focusing test method in projection lithography, belong to the nano-device manufacturing technology field in VLSI (very large scale integrated circuit) manufacture and optics Micrometer-Nanometer Processing Technology.
Background technology
Along with the development of extensive and VLSI (very large scale integrated circuit), application large-numerical aperture light projection photoetching objective lens and short wave length exposure light source, constantly break through projection lithography resolving power.Meanwhile, in order to reduce production costs and to enhance productivity, die size is from traditional 2, and 4inch (1inch=2.54cm) is excessively to 8,12inch, even overlarge area exposure.The raising of resolving power directly causes the sharply decline of effective focal length; In addition, the increase of die size has brought again the significantly increase of exposure area, thereby cause the further deterioration of defocusing amount, simultaneously, other defocus error sources (warpage of silicon chip, the landform of substrate, the thickness of resist self etc.) do not reduce, this significantly atrophy of allowance that all makes to focus, proposes to focus detection system the harsh requirement that nanometer scale high precision detects especially.
For the lower situation of focusing test accuracy requirement, mostly adopt the comparatively simple slit luminosity formula focal plane method of structural principle, can meet the occasion of sub-micrometer scale accuracy requirement, and for the focal plane of nanometer scale, laser interference focusing test technology, the Moire fringe method based on Tabo effect and photoelastic modulation method have been developed.Laser interference focusing test technology can not suppress the film interference that silicon chip process layer causes; The Moire fringe of laser interference focusing test technology, Tabo effect and photoelastic modulation method are all very easy to be subject to the impact of environment and the demodulator circuit of rear end complexity.
Summary of the invention
In order to solve existing technical matters, the object of this invention is to provide a kind of simple, high-level efficiency, nano level high precision focusing test method.
In order to realize described object, the invention provides a kind of nanometer focusing test method of Moire fringe Phase-Resolved Analysis, technology is put case and is comprised that illuminator introduces light path by optical fiber after expanding, through condenser Uniform Illumination mark grating, mark grating is through the first telecentric imaging system, again by prism imaging at silicon chip surface, after being reflected through prism, the second telecentric imaging system; By Amici prism, light path is divided into two, two light channel structures are identical, every light path is all passed through Transverse Shear cutting plate, and parallel flat formation interference pattern and target picture are by detecting Grating Modulation, through analyzer, again by photodetector and circuit demodulation, the movement of silicon chip position of focal plane causes the generation sinusoidal variations of modulation light intensity, according to the sinusoidal variations of two light path light intensity, obtains mark raster phase and changes θ, determine the translational movement Δ X of mark grating image, thereby obtain the variation delta Z of position of focal plane.
Further, the light distribution of the detection grating of a described light path is: I
1=A
1sin (θ), the light distribution of the detection grating of another light path is: I
2=A
2sin (θ+Δ θ).I wherein
1, I
2for the light distribution obtaining, A1, A2 is for exchanging amplitude, A1=A2; θ is that the phase place variation that causes mark grating is moved in position of focal plane, and Δ θ is the phase differential (Δ θ=90 degree) of two light paths.
Further, described two cycles of detecting grating should equate, and the cycle of mark grating should equal the grating cycle of two detection gratings.
Further, the phase difference θ of adjustable two light beams of the parallel-plate of described two light paths.
Further, described the second imaging system is by lens, the polarizer, and light ball modulator assembly, lens form.
Adopt the nanometer focusing test method of a kind of Moire fringe Phase-Resolved Analysis of the present invention, Amici prism is divided into two by light path, adjust phase phasic difference 90 degree that parallel flat makes two light paths, the phase place of obtaining mark grating according to sine and cosine changes θ, and then try to achieve the variable quantity Z of position of focal plane, control piezo stage motion and reach optimal focal plane position.In telecentric imaging system, add light ball modulator assembly, be equivalent to increase a high frequency carrier, greatly strengthen the anti-interference and noise resisting ability of focal plane.The method provides high precision, the measuring accuracy of high stability and desirable measurement range by comparatively simple structure and data processing.
Accompanying drawing explanation
Fig. 1 is litho machine structural representation;
Fig. 2 is focusing test measurement model figure;
Fig. 3 is schematic diagram of the present invention.
Embodiment
Below in conjunction with accompanying drawing, the present invention is described in further detail.
Fig. 1 is litho machine structural representation, wherein projection objective 2 by the information projection on mask 1 to silicon chip 4; 3 is nanometer focus detection system, is used for surveying the upper surface of silicon chip with respect to the relative position of the best focal plane of projection objective.5 for bearing the work stage of silicon chip.
Fig. 2 is focusing test measurement model schematic diagram, adopts principle of triangulation, and silicon chip Z-direction change in displacement is converted into the transversal displacement Δ X of mark grating image in detection system, by Δ X is detected, realizes focusing test.
In formula, pi/2-γ is incident angle.
Fig. 3 is the agent structure schematic diagram of focus detection system, from the optics of illuminator 1 output, after expanding, by optical fiber, introduce light path, through condenser 2 Uniform Illumination mark gratings 3, mark grating 3 pictures are after the first telecentric imaging system being comprised of lens 4 and 5, by prism 6, be imaged on silicon chip 7 surfaces (incident angle 83 degree) again, after being reflected through prism 8 and by lens 9, the polarizer 10, light ball modulator assembly 11, after the second telecentric imaging system that lens 12 form, by Amici prism 13, light path is divided into two.In the second telecentric imaging system, add light ball modulator assembly 11 to be equivalent to increase a high frequency carrier, increase the anti-interference and antimierophonic ability of system.Two light channel structures that are divided into by Amici prism 13 are identical, and energy is also identical.A light path is divided diffraction light to be cut to the orthogonal O light in polarization direction and E light by Transverse Shear cutting plate 131, form the Sine distribution light beam of two groups of mutual dislocation, by parallel-plate 132 formation interference patterns and target picture, via detecting grating 133, modulate, through analyzer 134, condenser 135, the movement of silicon chip 7 positions of focal plane causes the sinusoidal variations of modulation light intensity, then by photodetector 136; Another light path is divided diffraction light to be cut to the orthogonal O light in polarization direction and E light by Transverse Shear cutting plate 141, form the Sine distribution light beam of two groups of mutual dislocation, by parallel-plate 142, (adjustable phase is poor, make phase differential 90 degree of two light paths) form interference pattern and target picture via detecting grating 143 modulation, through analyzer 144, condenser 145, the movement of silicon chip 7 positions of focal plane causes the sinusoidal variations of modulation light intensity, by photodetector 146; Photodetector 136 and photodetector 146 light intensity out changes again via circuit demodulation, by AD capture card, is sent to PC.The sine and cosine of the light intensity collecting according to AD changes, and obtains mark grating 3 phase places and changes θ, determines the translational movement Δ X of mark grating 3 pictures, thereby obtains the variation delta Z of position of focal plane.
The light distribution of two light paths represents with following formula:
I
1＝A
1sin(θ)；I
2＝A
2sin(θ+Δθ)
I in formula
1, I
2the light intensity value of two light paths that obtain for AD Data Acquisition Card.A1, A2 is for exchanging amplitude, A1=A2; θ is the phase place variation that the mark grating causing is moved in position of focal plane, and Δ θ is the phase differential of two light paths.
In the course of the work, by adjusting parallel flat 132 and parallel flat 142, make it to differ 90 degree, I
2=A
2cos (θ).Thereby the phase place that can obtain mark grating 3 changes
translational movement Δ X=P* θ/2 π of the picture of mark grating 3, P is the cycle of mark grating 3, in system the cycle of mark grating 3 should with detect grating 133, the cycle of detecting grating 143 should equate.Finally, by triangle principle, obtain the change Delta Z of position of focal plane.
The above; be only the embodiment in the present invention, but protection scope of the present invention is not limited to this, any people who is familiar with this technology is in the disclosed technical scope of the present invention; can understand conversion and the replacement expected, all should be encompassed in of the present invention comprise scope within.
Claims (5)
1. the nanometer focusing test method of a Moire fringe Phase-Resolved Analysis, it is characterized in that: the method comprises that according to the direction of propagation of incident light illuminator introduces light path by optical fiber after expanding, through condenser Uniform Illumination mark grating, mark grating is through the first telecentric imaging system, again by prism imaging at silicon chip surface, after being reflected through prism, the second telecentric imaging system; By Amici prism, light path is divided into two, two light channel structures are identical, every light path is all passed through Transverse Shear cutting plate, and parallel flat formation interference pattern and target picture are by detecting Grating Modulation, through analyzer, again by photodetector and circuit demodulation, the movement of silicon chip position of focal plane causes modulation light intensity generation sinusoidal variations, according to the sinusoidal variations of two light path light intensity, obtains mark raster phase and changes θ, determine the translational movement Δ X of mark grating image, thereby obtain the variation delta Z of position of focal plane.
2. the nanometer focusing test method of a kind of Moire fringe Phase-Resolved Analysis according to claim 1, is characterized in that: the light distribution of the detection grating of a light path is: I
1=A
1sin (θ), the light distribution of the detection grating of another light path is: I
2=A
2sin (θ+Δ θ), wherein I
1, I
2for the light distribution obtaining, A1, A2 is for exchanging amplitude, A1=A2; θ is that the phase place variation that causes mark grating is moved in position of focal plane, and Δ θ is the phase differential of two light paths, Δ θ=90 degree.
3. the nanometer focusing test method of a kind of Moire fringe Phase-Resolved Analysis according to claim 1, is characterized in that: two cycles of detecting grating should equate, and the cycle of mark grating should equal the grating cycle of two detection gratings.
4. the nanometer focusing test method of a kind of Moire fringe Phase-Resolved Analysis according to claim 1, is characterized in that: the phase difference θ of adjustable two light beams of parallel flat of two light paths.
5. the nanometer focusing test method of a kind of Moire fringe Phase-Resolved Analysis according to claim 1, is characterized in that: the second imaging system is by lens, the polarizer, and light ball modulator assembly, lens form.
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| CN201410308999.6A CN104049474B (en) | 2014-07-01 | 2014-07-01 | Nano focus detection method for stacked gate stripe phase analysis |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105466359A (en) * | 2015-12-30 | 2016-04-06 | 中国科学院微电子研究所 | Precise surface shape measuring device |
| CN107810524A (en) * | 2015-06-26 | 2018-03-16 | 皇家飞利浦有限公司 | Rebuild for details in a play not acted out on stage, but told through dialogues and phase contrast CT robust |
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| JP3352249B2 (en) * | 1993-10-26 | 2002-12-03 | キヤノン株式会社 | Position shift detector |
| CN101169601A (en) * | 2007-11-21 | 2008-04-30 | 上海微电子装备有限公司 | Focusing leveling measuring system |
| CN102231046A (en) * | 2011-06-17 | 2011-11-02 | 中国科学院光电技术研究所 | Optical gate moire fringe focal plane detection method |
-
2014
- 2014-07-01 CN CN201410308999.6A patent/CN104049474B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3352249B2 (en) * | 1993-10-26 | 2002-12-03 | キヤノン株式会社 | Position shift detector |
| JPH07159125A (en) * | 1993-12-07 | 1995-06-23 | Canon Inc | Optical heterodyne measuring device and method using it |
| CN101169601A (en) * | 2007-11-21 | 2008-04-30 | 上海微电子装备有限公司 | Focusing leveling measuring system |
| CN102231046A (en) * | 2011-06-17 | 2011-11-02 | 中国科学院光电技术研究所 | Optical gate moire fringe focal plane detection method |
Non-Patent Citations (1)
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| 严伟等: "基于光闸叠栅条纹的纳米检焦方法", 《光学学报》 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107810524A (en) * | 2015-06-26 | 2018-03-16 | 皇家飞利浦有限公司 | Rebuild for details in a play not acted out on stage, but told through dialogues and phase contrast CT robust |
| CN107810524B (en) * | 2015-06-26 | 2022-05-17 | 皇家飞利浦有限公司 | Robust reconstruction for dark-field and phase contrast CT |
| CN105466359A (en) * | 2015-12-30 | 2016-04-06 | 中国科学院微电子研究所 | Precise surface shape measuring device |
| CN105466359B (en) * | 2015-12-30 | 2019-04-26 | 中科晶源微电子技术（北京）有限公司 | A kind of precision surface type measurement device |
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